A NEW RECOVERY TECHNIQUE FOR GAS-PRODUCTION FROM ALASKAN GAS HYDRATES

An enormous amount of natural gas is trapped in hydrate form in the North Slope of Alaska. Recently, these gas hydrates have been identified as an alternative natural gas resource. This resource, however, is extremely difficult to exploit. Recent studies have mainly focused on steam and/or hot-brine stimulation of gas hydrate reservoirs. Unfortunately, the presence of permafrost (leading to excessive heat loss to the surrounding) and high reservoir pressure make conventional thermal recovery techniques inadequate. This paper studies the feasibility of electromagnetic heating for dissociating solid gas hydrates. A series of numerical simulation runs was conducted to demonstrate the feasibility of the proposed gas recovery technique. For a wide range of reservoir parameters, gas recovery and the energy efficiency ratio (i.e., the ratio of energy of produced gas to heat injected) are computed. The effects of reservoir rock properties, hydrate zone thickness, the amount of the electric energy and the production/heating strategy were studied. Results were compared with those with steam and hot brine stimulation. Significantly higher energy efficiency is observed with electromagnetic heating. It is shown that the radius of heating did not have to be very large in order to develop a continuous stream of gas production. The maximum flow rate, however, was a function of electrical power and the well configuration.